This invention relates to releasable gripping or locking devices for use particularly, but not exclusively, in releasably arresting or locking .an elongate member, either flexible or rigid, against movement in one direction.
It also relates to releasable locking, coupling or support devices for use particularly, but not exclusively, in latching a load, e.g. in a raised position, so that tension in a hauling line can be relaxed, or releasably coupling together two parts, or releasably securing one part in or to another part or structure, or forming a rotary coupling between two parts, or providing a releasable load support.
U.S. Pat. No. 4,644,617, the disclosure of which is incorporated herein by reference, discloses releasable locking, coupling and support devices comprising two parts which are in, or can be brought into, a relatively slidable disposition, and interengageable latching means on the two parts. The latching means are engageable and disengageable automatically on relative movement of the parts in opposite directions. The latching means comprise an abutment on one of the parts, at least one rotary pawl on the other part to cooperate with the abutment in the latched condition and control means for positioning the pawl in a series of angular dispositions thereof during a latching or a release sequence of the latching means. The control means comprise resilient means provided on the same part as the pawl, to act on the periphery of the pawl, or a part associated therewith, to temporarily locate the pawl in said angular positions during the latching and release sequences.
In the devices of U.S. Pat. No. 4,644,617, the latching connection between the two parts is effected by the engagement of the pawl on one part with the abutment on the other part. The strength of the connection in the latched condition thereof depends on the strength of the pawl, requiring a relatively massive pawl for heavy load applications. Furthermore, when a single pawl is used there is an unbalanced seating of the latched parts. These disadvantages can be reduced to some extent by employing two or more latching pawls but this results in a more complicated construction.